library (AER)
data(CPS1985)
df <- CPS1985[ CPS1985$education==12, c("wage","experience")]
mean.exp <-mean(df$experience)
mean.exp
reg.1 <- lm(I(log(wage))~experience+I(experience^2),data=df)
reg.1
a <- c(0,1,2*mean.exp)
avg.eff.exp <- as.numeric(t(a)%*%coef(reg.1))
maxexp <- abs(coef(reg.1)[2]/(2*coef(reg.1)[3]))